(i) Field of the Invention
This invention relates to an articulable article clamp. More particularly, it relates to such a clamp in the form of an electrode clip for the connection of a lead cable from an electrocardiograph to an electrode which is temporarily secured to a human body.
(ii) Description of the Prior Art
There are many situations where it is desirable to clamp an electrode to an electrically conductive wire. In one specific instance, in order to ascertain electrical phenomena arising from physiological functioning, for example electrocardiographic data associated with the functioning of the heart in patient monitoring uses, it is necessary to apply sensory devices (known as electrodes) to the skin. The electrodes may be applied to the skin by a suction cup, aided by an electrically conductive cream, or they may be glued or taped to the patient's body. The electrode may be provided with a male pin or male snap fastener. Traditionally, the female portion of the snap fastener was intended mechanically to couple to the male portion. Several different types of cable fasteners have been used to couple electrical impulses from the electrode on a patient's body to a cable connected to an electrocardiograph or other monitoring device. In all such electrical connectors in general, and in this case in particular, it is important that a good connection be made by the electrode clip between the electrode and the lead cable.
Many deficiencies exist in such cable fasteners. For example, it was found that in many instances the resulting electrical connection was not noise-free and fatigued easily, causing loose connections. Additionally, since existing cable fasteners were connected by pressing downwardly on the male electrode stud, a hard push was often necessary to make a good connection. The prior types of snap fasteners, though simple and inexpensive to produce, were difficult to repair.
One type of fastener which was developed to attempt to solve this problem was a hairpin and turn-cam fastener. This type of fastener made a good electrical connection when new and allowed simple application. The joint between cable and fastener was by a tubular solderless connector which was crimped on the fastener and the cable, and then covered with shrink tubing. However, this fastener suffered many dificiencies. The fastener was expensive to make. It offered very little strain relief, and physicaly fatigued early in life, thereby causing loose connections. The electrical contact surface consisted of only four pin point surfaces which wore away very quickly. The length of the connector provided leverage which, when lifting the cable, often pried the connector off the snap. Because shielded wire cables work best when the exposed metallic fastenings were as small as possible, the length of this type of fastener was much too great to enhance the benefits of shielded cable.
In an attempt to solve this problem, the cable fastener for electrocardiograph electrodes disclosed in U.S. Pat. No. 3,829,826 issued Aug. 13, 1974 to D. M. Brown et al was provided. In that cable fastener, there was included a metal bracket and a spring wire joined together. The metal bracket had a clearance hole which fit over the male snaps and had an offset to allow connections to cup-mounted snaps. The spring wire provided mechanical retention and, by holding the bracket in contact with the snap, a durable electrical connection. A partial loop on the spring wire formed a finger pad for engaging and disengaging the fastener from the snap. The cable fastener mated with the male snap of an electrocardiograph electrode, for example, as it was mounted on a flat surface or seated in a cup depression. While this cable fastener was successful when new, as the spring became less resilient during use, it became less effective. On the other hand, if the spring were made strong initially, it would be more difficult to use.
In a second solution to this problem, that provided by U.S. Pat. No. 3,895,635 issued July 22, 1975 to G. F. Justus et al, a connector was provided which had a non-conductive body having one end of a cable located therein, carrying an electrical contact plate against which a stud of an electrode was locked by a non-conductive cam lever pivotally mounted on the body portion.
In a third solution, that provided by U.S. Pat. No. 4,026,278 issued May 31, 1977 to J. R. Ricketts et al, the electrode stud was inserted in a keyway hole in a connector secured electrically to the end of a cable, and held in place by a sprung back-up plate.
These latter two solutions, however, suffer the practical deficiency that in securing the connector to the electrode stud some pressure would be applied to the electrode.